1. Field of the Invention
The present invention concerns safety hooks which lock automatically in which locking is assured by a transverse locking lever engaging between a pivoting closure finger and an opposite portion of the safety hook body to selectively prevent pivoting of the locking finger in the opening direction.
2. Description of the Prior Art
Safety hooks of the above kind that are locked automatically by a transverse lever are described in documents FR 2 439 330 A and FR 2 485 658 A.
In both of the above documents, the safety hook comprises a safety hook body having an opening selectively closed by a pivoting finger articulated at its first end about a transverse rotation pivot, with a transverse locking lever mounted to be able to pivot about a lever pivot between a locking position, in which it is engaged between the pivoting finger and an opposite portion of the body to prevent rotation of the pivoting finger and toward which it is biased by spring means, and an unlocked position, in which it releases the pivoting finger so that it can rotate in its opening direction. The pivot of the locking lever is in said opposite portion of the body, and the free end of the locking lever engages over the pivoting finger.
In document FR 2 485 658 A, the locking lever is generally rectilinear and is entirely engaged between the pivoting finger and the opposite portion of the body, near the free end of the pivoting finger. As a result, the locking lever reduces the opening capacity of the safety hook, and constitutes a component that is relatively inconvenient to operate. This device is therefore not suitable for mountaineering use or for working in high places, where safety conditions must be complied with without necessitating difficult and irksome intervention by the user. What is more, there is nothing to prevent pivoting of the locking lever, which can therefore be unlocked unintentionally.
In document 2 439 330 A, the transverse locking lever is at a greater distance from the free end of the pivoting finger, which improves the opening capacities. Also, the locking lever is L-shaped with a longitudinal branch that projects radially beyond the opposite portion of the body, which facilitates manipulating the locking lever. However, the free end of the locking lever comprises two parallel branches disposed each on opposite sides of the pivoting finger to engage over lateral bosses on the pivoting finger to lock the safety hook. The parallel branches at the end of the locking lever constitute relatively weak components that may be deformed in use. If they are deformed away from each other, there is a risk of inhibiting all locking capacity of the locking lever, so compromising the reliability and the safety of the safety hook. What is more, the locking lever projects away from the body in an exaggerated manner and constitutes a protruding component that can interfere with use and to which force can be applied unintentionally.
In the above document, a sliding ring, mounted on the opposite portion of the body, can immobilize the locking lever to prevent it pivoting toward the unlocked position. The drawback of this is that it is therefore necessary to manipulate the locking ring each time so that the locking lever can then be manipulated to unlock the safety hook.
The problem addressed by the present invention is that of the designing a new hook structure which is locked automatically by a transverse locking lever, which assures both reliable and effective locking and a maximum opening capacity of the safety hook, and which assures selective immobilization or permanent releasing of the locking lever, enabling the user to choose between single locking or double locking. The change from the immobilized state to the released state must be effected simply and quickly by intentional action of the user.
The invention equally aims to design a safety hook structure of the above kind that is particularly simple and inexpensive to manufacture.